Batesian and Mullerian Mimicry

Many insects resemble other species. This occurs for several different reasons. The most obvious reason is that the different species are closely related. For example, there are 8 species of social wasp found in Britain. They are all very similar and need close inspection to differentiate between the species. One species, the Cuckoo Wasp, takes advantage of this similarity and lays its eggs in the nests of other wasps, for them to bring up the young. This is not true mimicry, however, as the species involved are closely related. A second reason why different species may look similar is convergent evolution. Here, completely unrelated species independently develop the same structure and form, since it is the ideal type for the particular niche that the species fills. It is difficult to find true examples of this in the British insect fauna.
We now arrive at true mimicry. This has been classified into 2 distinct types. These are known as Batesian and Mullerian mimicries. They are named after the naturalists who first described them.
Henry Walter Bates was an English biologist who described a type of mimicry in tropical butterflies in the 1850's. In this form of mimicry, one species is harmful and the other is harmless. An example of this form of mimicry includes the mimcry of Wasps by other insects. The Wasp is known as the model and the other species the mimics. The model escapes from predators by virtue of its sting. It advertises its sting with bright warning colours. Once a young bird or other predator has attempted to tackle a Wasp, it learns to avoid any insect with these bright markings. The mimic is thus also avoided, despite its harmless nature. The mimic must be around at about the same time as the model. The model is preferably commoner earlier in the season so young predators are more likely to be exposed to the model and learn avoidance behaviour.
Fritz Muller was a German zoologist who described a different type of mimicry in 1878. In this form, several unpalatable species share a similar warning pattern. The predator need only be exposed to one species for it to avoid all of them. Thus all the mimic species benefit.
Distinction between the types of mimicry may not be clear cut. Species that seem to be Batesian mimics may be unpalatable to some predators and thus be Mullerian mimics in selected instances.

From left to right are the Common Wasp, Vespula vulgaris, and some of its mimics - the Hornet Moth, Sesia apiformis, the Wasp Beetle, Clytus arietis, and the Hoverfly, Syrphus ribesii.

This is adapted from the Peregrines Productions plate GEN1 'Wasp Mimics'.
You can see details of this and other plates in the catalogue